The present invention relates to a magnetic disk device and, more particularly, to a magnetic disk device having a mechanism for loading/unloading a magnetic head supporting mechanism.
Disk devices in the prior art include a system in which a slider is withdrawn (unloaded) out of the disk surface during the suspension of the device, when a disk reaches its normal speed of revolution, the slider is loaded onto the disk surface from its withdrawal position, and when the disk is to be stopped, the slider is unloaded to the withdrawal position prior to slowing-down of the revolution of the disk.
Japanese Patent Unexamined Publication No. 8-263946 discloses a construction in which a ramp corresponding to a withdrawal means provided with a sliding surface inclined toward the disk is provided, and a semispherical-shaped dimple (convex-shaped portion) is provided at the tip of a suspension to slide on the sliding surface.
In the prior art referred to above, the dimple is pressed against a ramp by a pressing load, and frictional forces act on the sliding parts because the dimple runs on the ramp in this state. Accordingly, the ramp and the dimple will wear due to a repeated compressive stress caused by the pressing load and shearing stresses caused by the frictional forces.
In the prior art, the same portion of the dimple slides on the same track on the ramp during loading or unloading. Since the direction of the frictional forces are directed in opposite directions during loading or unloading, those shearing stresses, to which the same portions of the ramp and the dimple are subjected, are alternating (changing in plus and minus sides about zero), thus resulting in a correspondingly greater amplitude of stress.
When the number loading/unloading times (one reciprocation is counted as one round) is N, the ramp and the dimple slide as frequently as 2N times, thus the number of sliding being great.
Wear of the ramp and of the dimple not only adversely affects the loading/unloading performance, but also the resulting worn powder enters into a gap between the slider and the disk, highly possible to cause an irrecoverable failure of the whole device.